Logs are typically processed in two or more phases. The first phase, or primary breakdown, involves chipping/cutting the logs into one or more pieces. Additional cuts are made to some or all of the pieces in the second phase, or secondary breakdown. Due to their generally cylindrical shape, logs are often cut to obtain side boards from the curved outer periphery of the log. The side boards are produced at a desired width, and are subsequently trimmed to a desired length downstream of the secondary breakdown system.
Some processing lines are configured to produce side boards in the primary breakdown phase. These primary breakdown systems usually have a chipper, a profiler, and a saw module. The chipper chips open faces along opposite sides of the log to form a cant. The profiler chips the sides of the cant to form the profile of the desired side boards. The saw module cuts through the cant to release the side boards from the remainder of the cant.
Other processing lines are configured to produce side boards in the secondary breakdown phase. In common configurations the primary breakdown system has a chipper and a saw module, and the secondary breakdown system has an edger. The chipper chips open faces along opposite sides of the log, and the saw module cuts through the resulting cant to sever flitches from the remainder of the cant. The edger cuts the flitches longitudinally to produce the desired side boards.
In the first configuration, the longitudinal sides of the side boards are formed by the profiler before the side boards are cut from the cant. In the second configuration, the longitudinal sides of the side boards are formed by the edger after the flitch has been cut from the cant.